1. Field of the Invention
This invention relates generally to solar mirrors and, in one particular embodiment, to a solar mirror having improved anticorrosion properties for the metallic layer of the mirror.
2. Technical Considerations
With the increasing costs of fossil-based fuels, solar power is becoming a more commercially acceptable and economically viable source of energy. One known application is using mirrors to concentrate solar power for electrical generation. Mirrors having high reflectance of solar radiation are used for “concentrated solar thermal power” (CSTP) installations. One conventional system uses curved parabolic solar mirrors to concentrate solar energy onto tubes positioned along a focal line. A heat transfer medium in the tubes carries the absorbed heat energy to a generator station where it is used for power generation. Another conventional system uses a solar tower in which a number of flat solar mirrors direct solar energy at a particular location on the tower. The heat generated by the focused solar energy is transferred to a working fluid, such as sodium, and the heated working fluid is used for power generation. A further application of such mirrors is for “concentrated photovoltaics” (CPV). In this application, mirrors focus or concentrate solar energy onto high-efficiency photovoltaic (PV) devices, thereby improving the energy output per device.
In these systems, it is desirable that the mirrors reflect as much solar energy as possible. It is also desirable that the mirrors have as long a commercial life as possible to preclude frequent changing of the mirrors.
Conventional solar mirrors utilize a reflective metal layer to reflect the solar energy. These mirrors are positioned outdoors in an array that can include hundreds or thousands of mirrors. Since the mirrors are exposed to environmental conditions, such as rain, snow, airborne contaminants, etc., a problem with these conventional solar mirrors is that the reflective metal layer can become corroded or degraded by attack from moisture or airborne contaminants. Some solar mirrors include a casing or backing to help keep out such materials. However, with age and wear, the backings can crack or break, allowing moisture to enter and corrode the metal layer. This corrosion decreases the reflectance of the mirror and shortens the commercial life of the mirror.
Therefore, it would be advantageous to provide a reflective article, such as a solar mirror, with increased resistance to corrosion.